There is currently tremendous optimism and enthusiasm for cell-based therapies for heart disease. However, cell therapy is in its early stages, and various questions remain. For example, the identification of those patients who benefit most from cell therapy, the optimal cell type and number for patient with acute and chronic diseases, the best time and way of cell delivery, and the mechanisms of action by which cells exhibit beneficial effects, need to be further evaluated.”
As summarized in a recent review (Segers and Lee, 2008), there were 31 reports of clinical trials involving cell therapies in patients with MI. Of these, 14 reported statistically significant improvement in left ventricular ejection fraction, one noted decreased mortality, two did not provide sufficient data to evaluate, and 14 reported no significant improvement in ejection fraction. It is clear, however, that the significance of these results is extremely difficult to evaluate because a variety of different cells were used, including: bone marrow nucleated cells; circulating progenitor cells; CD133 hematopoietic stem cells; CD34 hematopoietic stem cells; skeletal myoblasts; MSCs; a combination of MSCs and endothelial progenitor cells; and unspecified bone marrow cells. The different studies also used significantly different criteria for selecting and evaluating patients, the nature of their controls, the number of patients enrolled, mean follow-up times, the number of cells administered, and the routes of administration. Therefore, the best that one can conclude at the moment is that cell-based therapies offer promise for patients with cardiac disease, but many aspects of the potential therapies require further study (see Segers and Lee, 2008; Dimmeler & Leri, 2008; Charwat et al., 2008; Burt et al., 2008). There is a need to better define the optimal cells, routes of administration and the mechanism by which MSCs can repair the heart. The technical problem underlying the present invention was therefore to overcome these prior art difficulties by identifying a suitable cell type for cell-based therapies for heart disease, and by identifying at least one cell-based factor responsible for improved outcomes in heart disease. The solution to this technical problem is provided by the embodiments characterized in the claims.